Compliance analysis of transversely asymmetric flexure hinges for use in a piezoelectric Scott-Russell microgripper

Abstract

Notch flexure hinges with longitudinal/transverse asymmetries can be widely found in compliant mechanisms to balance the performance trade-offs. However, the transverse asymmetry often leads to difficult analyses of kinetostatics and dynamics. In this paper, a miniaturized piezoelectric gripper featuring reversed Scott-Russell compliant amplifier with transversely asymmetric single-notched flexure hinges is designed for use in confined spaces. The compliance and vibration characteristics of the transversely asymmetric single-notched flexure hinges are quantitatively analyzed by a new transfer matrix method. The proposed theoretical methodology involves discretizing the transversely asymmetric flexure hinge into a series of constant beam segments with non-coaxial nodes, which enables a straightforward modeling process and hence simplifies the kinetostatic and dynamic analyses of compliant mechanisms comprised of complex flexure hinges. Comparative validations with respect to the finite element simulation and experiments confirm the advantages of easy operation and small-scale equation sets of the proposed modeling method. As to the designed piezoelectric microgripper with single-notched flexure hinges, the jaw displacement amplification ratio of 20 and resonance frequency of 1250 Hz has been experimentally tested with a small size of 38 mm × 15 mm × 7 mm.